ED Cowell on sat 22 feb 97
There have been many messages regarding the dangers of manganese dioxide in
the studio. For 20 years or so I have been using speckled clay that
contains manganese. Do I need to panic?
Laurie Cowell,
Waterloo, Ontario, Canada.
Dannon Rhudy on sun 23 feb 97
Laurie,
No point to panic. Many potters use clays with manganese in the
body; some have done so always and lived into their nineties
no doubt without any visible effects from the manganese. I don't
use anything with manganese in it. Period. BUT
if you are uncomfortable with it, change the claybody. It is
absorbed through the skin, and a breathing hazard. Expect there
is at least some in various surfaces, in the air as dust in your
studio, and you probably don't throw with gloves on.
Dannon Rhudy
----------------------------Original
message----------------------------
There have been many messages regarding the dangers of manganese
dioxide in
the studio. For 20 years or so I have been using speckled clay
that
contains manganese. Do I need to panic?
Laurie Cowell,
Waterloo, Ontario, Canada.
Janet H Walker on tue 25 feb 97
I feel compelled to comment on this as a representative post in this
thread:
...absorbed through the skin, and a breathing hazard. Expect there
is at least some in various surfaces, in the air as dust in your
studio, and you probably don't throw with gloves on.
From my reading of the hazards sheets, the major hazard with manganese
dioxide is from dust and fumes. Both of these terms have technical
definitions. The stuff that is in the clay as speckles is granular
manganese not dust. I suppose one could take the point of view that
manganese is manganese and therefore all forms are equally toxic. But
it is my understanding at least that the granular form doesn't just by
itself automatically collapse down into dust. It can only get into the
dust form through grinding. I expressed the preceding as a question to
Monona once and I believe that she basically said that I had the idea.
So if you really like the manganese speckles in clay (I know I do) then
look carefully at the warnings to see which really apply to what. The
clay manufacturers send the clay with the manganese speckles out in
boxes that are stamped with AP Non-toxic. I assume they would not do
that if it were false although I guess there is never a guarantee of
truth in labelling.
Thoughtfully,
Jan Walker
Dan c Tarro on wed 26 feb 97
I have looked back in my old copies of Clay Times and Ceramic Monthly to
find an article that someone had written about this. It was published
within the last two years. Couldn't find it. Maybe someone might
recognize it and tell us more about what was written and where. It had
to do with an artist using granular manganese in his clay and being
poisoned by the sanding of his pieces after they were bisqued.
I know my wife reminds me constantly that I have lost something. Memory
is a passing thing.
Dan Tarro
Oak Tree Stoneware
Ham Lake, Mn
ret on wed 26 feb 97
I would suspect also, like Jan Walker, that granular mn in clay
is probably less likely to turn into dust. Is it worth taking the chance?
I would be more concerned, however,
about inhaling the mn fumes during firing of the work. Whether the mn is
in the clay or in the glaze,and no matter in what form, it would give off
fumes I, personally, would do everything to avoid.
Another way to get exposed to mn fumes: Fibre Raku kilns are often wired
together with stainless steel wires or buttons. The supplier told me that
when that metal gets heated it lets off a substantial amount of mn fumes.
He thought (!!) that probably those fumes would only be produced at the
intial heating and then burn off.
I've not asked Monona about that one.
ELKE BLODGETT email: eiblodge@freenet.edmonton.ab.ca
12 Grantham Place
St. Albert, AB T8N 0W8
403 (458-3445); 403 (727-2395)
gina on mon 21 oct 02
I have been reading several postings about manganese and am now wondering
about the health hazards of using my favorite "speckled" clays which contain
manganese. How does the danger compare to using manganese in a glaze? I
understand that with the glaze there is the issue of handling the powder
very carefully (mask, gloves, etc) when mixing, and that the fumes are
dangerous when firing. I would guess that clay dust from speckled clay is
more dangerous than non-speckled clay dust? and are the fumes just as
dangerous from speckled clay (with clear glazes) as from manganese glazes
over non-speckled clay?
gina, in south florida, trying to decide which clay to stick with
JP on sat 18 feb 06
I have been using Standard clay 112 for years now and I have recently
heard that the Manganese specs found in the clay are toxic, and should not
be used. I'm hoping someone has some info to help me decide if the
Manganese is any worse for you than the other materials found in clay
bodies. Inhaling Silca is bad for you also?
Vince Pitelka on sun 19 feb 06
>I have been using Standard clay 112 for years now and I have recently
> heard that the Manganese specs found in the clay are toxic, and should not
> be used. I'm hoping someone has some info to help me decide if the
> Manganese is any worse for you than the other materials found in clay
> bodies. Inhaling Silca is bad for you also?
This has been discussed many times on Clayart and there is a wealth of
information in the archives. There is no danger from manganese particles in
the clay. Skin absorption is not the problem. The route of toxic entry is
via inhallation of fine dust or the breathing of fumes produced during
firing, and those are both quite dangerous. Yes, silica dust is very
dangerous, and you should take precautions to avoid ever breathing any form
of dust from clay or ceramic materials.
- Vince
Vince Pitelka
Appalachian Center for Craft, Tennessee Technological University
Smithville TN 37166, 615/597-6801 x111
vpitelka@dtccom.net, wpitelka@tntech.edu
http://iweb.tntech.edu/wpitelka/
http://www.tntech.edu/craftcenter/
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